The Excel LOGNORM.INV function returns the inverse of the lognormal cumulative distribution — given a probability, it returns the x-value at that percentile. It reverses LOGNORM.DIST.
Syntax
| Argument | Description | |
|---|---|---|
probability | Required | A probability between 0 and 1 (exclusive of the exact endpoints). |
mean | Required | The mean of ln(x) — the average of the natural logarithm of the variable. |
standard_dev | Required | The standard deviation of ln(x). Must be greater than 0. |
How to use it
LOGNORM.INV answers the percentile question: “below which value does this fraction of the lognormal distribution fall?” It is the exact inverse of LOGNORM.DIST(...,TRUE).
The mean and standard_dev describe the distribution of ln(x), so the median always equals EXP(mean). Feed the cumulative output of LOGNORM.DIST back into LOGNORM.INV and you recover the original x.
Probability bounds: the first argument must be strictly between 0 and 1. A value ≤ 0 or ≥ 1 returns #NUM!.
Try it: interactive demo
Pick a LOGNORM.INV example to see the formula and its result.
Practice workbook
Frequently asked questions
What does LOGNORM.INV return?
LOGNORM.DIST with cumulative set to TRUE.Are mean and standard_dev for x or ln(x)?
Why does LOGNORM.INV return #NUM!?
#NUM!.How do LOGNORM.INV and LOGNORM.DIST relate?
LOGNORM.DIST(x,mean,sd,TRUE) gives a probability, and feeding that probability into LOGNORM.INV(prob,mean,sd) returns the original x.Master functions like this in one day
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